1. Field of the Invention
The present invention relates to circuit boards which are installed in computer systems.
2. Description of the Prior Art
Many computers and computer systems employ what are called "mother boards," "system boards," or "back planes" which contain signal busses and electrical connectors. The busses and connectors are interfaces which are used to allow additional circuit boards to be used in the computer system so that different configurations and expansions of the system can be developed. In order to allow the additional circuit boards and the circuitry contained thereon to function correctly, specifications relating to the mechanical connections, the number of pins and arrangement, the electrical requirements, and the signal protocol and meaning are developed for each interface. Some interface or slots in a given system may have a particular meaning and have a different specification, while in other systems all of the slots or interfaces may be similar.
As a result of the development of these specifications, what is referred to as an interface standard is developed for use with each computer or computer system. Because of the great proliferation of different computer system designs and different busses and interfaces used in these systems, there are a large number of interface standards for which circuit boards must be developed. Generally the interface standards for different systems have different arrangements and have different timing, voltage and signal content characteristics. Many of the interfaces use a plated card edge on the circuit board and edge connectors on the mother board to perform the connection, but the number of pins or contacts, the spacing of the contacts and the number of sets of contacts varies from standard to standard. Other designs use plug and socket or pin and socket connectors on the circuit boards with complementary connectors mounted on the mother boards, again with the physical parameters such as the number of rows of pins, the number of pins per row, the pin spacing, the number of connectors varying between standards.
While the interface standards are different in many respects, in many respects there are commonalities between the different systems, such as the speed of the components, the word size of the information being transferred, the functions being performed by the additional circuit boards and other areas. Therefore a great number of similar but different circuit boards are developed for the varying interface standards. This great number of boards results in increased production costs due to lack of volume and increased inventory costs because of the need to stock different styles and types of boards for each system. Additionally, design costs are increased because of the amount of time required to properly develop and design a circuit board to work with the different standards.